Apparatus for drawing thread-shaped products



June 16, 1964 L. MAASKANT 3,137,

APPARATUS FOR DRAWING THREAD-SHAPED PRODUCTS Filed Sept. 29. 1961 INVENTOR.

LEENDERT MAASKANT 526M Maw- ATTORNEY United States Patent Office 3,137,033 APPARATUS FOR DRAWING TAD-SHAPED PRODUCTS Leendert Maaskant, Emmen, Netherlands, assignor to Algemene Kunstzijde Unie N.V., Arnhem, Netherlands, a corporation of the Netherlands Filed Sept. 29, 1961, Ser. No. 141,777 Claims priority, application Netherlands Oct. 7, 1960 6, Claims. (Cl. 18-43) This invention relates to an apparatus for drawing continuously moving filaments, threads, yarns, ribbons and similar filamentary products having a basis of thermoplastic linear polymers. More particularly, this invention relates to a drawing apparatus comprising a feeding device, a drawing device and a discharge device.

In the drawing of thread-shaped products having a basis of synthetic thermoplastic linear polymers, the products are withdrawn by the discharge device at a rate of speed greater than that at which they were supplied by the feeding device. During this drawing process, a longitudinal orientation of the polymeric molecular chains in the thread-shaped product occurs. The tensile strength of these thread-shaped products is greatly increased as a result of this orientation.

In order to obtain a uniformly drawn product, use is very often made of a drawing device, comprising one or more pins, rods, or pin-like members-about which filaments, threads, yarns, ribbons and the like are adapted.

to be wrapped and drawn. In the portion of the threadlike product in surrounding contact with these members, there is a uniform increase in tension up to the point at which the thermoplastic material starts to yield. At this point, the thermoplastic material exhibits an abrupt decrease in cross-sectional area. This abrupt decrease is termed a necking down in the art. Since, theoretically, this necking down always takes place at substantially the same portion of the thread-shapedmcmber, the thickness of this member will be more uniform after drawing over a draw-pin than in the case where drawing and orientation are carried out without the use of such a pin-like drawing device.

In practice, however, it appears that not all drawing devices produce the same high uniformity of the product. Moreover, some drawing processes appear to be more satisfactory than others, from a commercial standpoint. With the thought of producing a better product, a great many different drawing devices have already been tried and suggested in the art.

It is known that a great many factors may influence the outcome of the drawing process. For example, the radius of curvature of the drawing pin itself, its ambient temperature, the area of surface contact with the threadshaped material, pin surface conditions and the material of construction of the drawing pin, are all variables that may effect the outcome of the product.

To this end, drawing devices have already been suggested that comprise a thick pin, which may or may not be heated, and which measures 75 to 100 mm. in diameter. Another drawing device having approximately the same diameter has been achieved by employing a combination of several mutually parallel pins. In the lattercase, several pins are arranged in a circular formation in order that they may be circumscribed by the material to be drawn. In order to obtain a uniform ambient temperature in these pins, they may be heated by a centrally ner.

However, there are drawbacks inherent to all these known devices. It has been found, for instance, that the single pin device gives rise to a rather high number of filament ruptures and faults per kilogram of drawn product. On the other hand, the plural block mounted parallel pin device is objectionable since it occupies a great deal of space, is costly to produce, and is expensive and cumbersome in use since its greater weight requires more supporting structure. It has also been found that this device is subject to mechanical failure due to the great number of pins employed. Moreover, the use of this parallel or multiple pin device results in a less uniform product since drawing or necking down may occur at different points simultaneously, followed by a necking down occurring at a single point. A plurality of draw points will obviously produce a larger product in crosssection than a single draw point since the drawing tension or drawing force is spread over a greater surface area due to the plurality of necks or shoulders. That is, the reduction in'the diameter of the thermoplastic material is inversely proportional to the force applied per unit area. Consequently, these prior art devices will produce a product having a continually varying diameter along the length of the drawn product.

Accordingly, it is an object of this invention to do away with the drawbacks of the prior art drawing devices.

It is another object of this invention to provide a draw ing device that will permit the uniform production of drawn filaments, threads, yarns, ribbons and the like.

Another object of this invention is to provide a drawing device which may be simply adapted to existing drawing machines. V

A further object of this invention is to provide an apparatus for producing drawn thread having high strength, low elongation and low shrinkage, from synthetic thermoplastic linear polymers.

Still a further object of this invention is to provide a drawing device that will permit the uniform and continuous drawing of synthetic linear polymer materials, and the consequent production of higher quality goods than has been known heretofore.

Other objects and advantages will become apparent to those skilled in the art with reference to the following detailed description.

The drawing device of this invention comprises two substantially parallel cylindrical pins that are placed next to and in contact with each other. Surprisingly, it has been found that this extremely simple embodiment of a drawing device gives rise to a remarkable decrease in the number of faults in the drawn product if the same is wrapped a full turn around these combined pins. Preferably, but not necessarily, these pins are of the same uniform diameter.

This invention also relates to a drawing machine employing these pins.

It has been found that the uniformity of the drawn product of this invention is even greater than when the same product is drawn over a device comprising a series of pins that are substantially arranged in a circle. Particularly good results are obtained when the pins of this invention have a round cross-section measuring more than 10 mm. in diameter and preferably about 15 to 25 mm. in diameter. The material used for the construction of these pins may be porcelain, glass or chromium plated metal. Preference, however, is given to pins constructed from a ceramic material containing at least 99% of titanium dioxide (TiO In using the device of this invention, it has been found that the number of faults can be kept particularly small if the surface of these pins is highly polished.

By choosing the relative positions of these pins such that they are substantially axially parallel or only cross Patented June 16, 1964' each other at a very small angle, the thread-shapedp1oducts being drawn on and off these pins will be kept clear of each other in a manner well known in the art. The same type of separation is accomplished by placing a separator roller at a slight angle with respect to a drawing godet.

The device of this invention will be more clearly understood with reference to the figure of the drawing which shows in perspective a diagrammatic embodiment of an apparatus according to the invention.

In the drawing, the numeral ll refers to a thread tensioning device over which a running length of a threadshaped member 2 is fed from a supply bobbin (not shown) to a feeding device comprising a feed roller 3 and pressure roller 4. Feed roller 3 is driven by a motor (not shown) in a manner well known in the art. To prevent slippage of the thread-shaped member 2 over the roller 3, pressure roller 4 is caused to bear against the roller 3. The surface of the roller 4 is composed of an elastic materiahsuch as a natural or artificial cork material, synthetic rubber or natural rubber. The roller 4 is supported by oscillating arms 5, only one of which is shown. Pressure roller 4 is not self-driven, but is rotated by reason of frictional contact with roller 3.

The filament, thread, yarn or ribbon 2 is kept in contact with the pressure roller 4 at an angle of wrap of more than 180 with the aid of a thread guide 6. To prevent cutting or frictional wear of rollers 15 and 4, the thread guide 6 is traversed slowlyin a direction that is longitudinal to the movement of the pressure roller 4. After the threadhas left the feed roller 3, it is wrapped a single turn around the drawing device 7 and subsequently progresses to the discharge device where it is wrapped a few turns around a draw godet 8 and idler roller 9. Draw gode't 8 rotates at a circumferential speed in excess of that of the feed roller 3 to accomplish the drawing action. By means of the guiding action of idler or separator roller 9, the centre line of which crosses the axis of draw godet 8 at a small angle, the wraps around the draw godet 8 are kept spaced in a manner that is well known in the art. The drawn thread-shaped member 2 is then passed from the draw godet 8 to a ring twisting spindle or take-up device (not shown) by means of which it is twisted and wound onto a bobbin or package (not shown) in a manner well known in the art.

The drawing device 7 comprises two circularly cylindrical pins 10 and 11 measuring 19 mm. in diameter and arranged substantially parallel to, and in contact with each other.

It is a preferred embodiment of this invention that these two pins are of the same or identical diameter.

However, it will be obvious to one skilled in the art that the relative diameters of these pins may be varied to a certain extent without departing from the spirit or scope of this invention.

Although the pins shown measure 19 mm. in diameter, this invention is operative with pins of substantially equal diameter within the range of about 10 to 25 mm. in diameter.

Preferably, but not necessarily, these pins are composed of a ceramic material which contains more than 99% of Ti The surfaces of the pins are highly polished.

For the purpose of illustrating the improvements that are obtained with the drawing device of this invention, there follows below a table showing the total number of faults that occurred in packages containing yarns that were drawn over the combined pins and 11, as compared with identical yarns that were drawn over a single pin having the same cumulative or total diameter. The test was carried out with 210, 420 and 630 denier polyamide yarns composed of 6 denier filaments and 4 preferably of 6 denier nylon 6 filaments The table enumerates the total number of faults contained in each kilogram of yarn treated.

210 420 630 Denier Denier Denier Yarn Yarn Yarn Single Pin Device 0. 50 0. 310 0.55 Fault per Kilogram. Double Pin Device 0.33 0.075 0.25 Do.

It is obvious from the results tabulated above that a considerable decreasein the number of faults per kilogram resulted from the use of the double pin device of this invention.

.It also appeared during this test that no improvement in the results were obtained by using a single pin having a diameter larger than the cumulative diameter of the double pin device.

Although the drawing device described herein is primarily intended for use in drawing thread-shaped products of linear synthetic polyamides, it will be apparent to those skilled in the art that the device of this invention can be employed for the drawing and orientation of other thermoplastic materials. It is also apparent that additional guides, rollers, clamps, braces and even heating devices may be employed in the device of this invention. Other embodiments employing the principles herein disclosed will become apparent to those skilled in the art. Accordingly, it is intended that the spirit and scope of this invention be limited only to the extent set forth in the following claims.

What is desired to be secured by Letters Patent is:

1. An apparatus for continuously drawing a running length of a synthetic filamentary material which comprises a feeding device for undrawn'filamentary material, a drawing device, and a discharge device for drawn filamentary material, said drawing device being located in the path of the filamentary material passing between the said feeding device and said discharge device and comprising at least two essentially cylindrical pins, said pins being arranged so that the outer surfaces thereof are contacting and the axes thereof are substantially in parallel, and said feeding device and said discharge device being adapted to apply drawing tension to said filamentary material as it passes over .said drawing device.

2. The apparatus according to claim 1 wherein each of said pins has a diameter in the range of from about 15 to about 25 mm.

3. The apparatus according to claim 1 wherein at least the outer surfaces of said pins are composed of a ceramic material.

4. The apparatus according to claim 3 wherein said ceramic material is at least 99% titanium dioxide.

5. The apparatus according to claim 1 wherein the outer surfaces of said pins are highly polished.

6. The apparatus according to claim 1 wherein the number of said pins is 2, each of said pins has a diameter in the range of about 15 to about 25 mm., and at least the outer surfaces of said pins are composed of a ceramic material.

References Cited in the file of this patent UNITED STATES PATENTS 2,296,394 Meloon Sept. 22, 1942 2,369,266 Thurnauer Feb. 13, 1945 2,611,923 Hume Sept. 30, 1952 2,778,058 Gabler Jan. 22, 1957 2,859,472 Wincklhofer Nov. 11, 1958 2,993,260 Boerma July 25, 1961 

1. AN APPARATUS FOR CONTINUOUSLY DRAWING A RUNNING LENGTH OF A SYNTHETIC FILAMENTARY MATERIAL WHICH COMPRISES A FEEDING DEVICE FOR UNDRAWN FILAMENTARY MATERIAL, A DRAWING DEVICE, AND A DISCHARGE DEVICE FOR DRAWN FILAMENTARY MATERIAL, SAID DRAWING DEVICE BEING LOCATED IN THE PATH OF THE FILAMENTARY MATERIAL PASSING BETWEEN THE SAID FEEDING DEVICE AND SAID DISCHARGE DEVICE AND COMPRISING AT LEAST TWO ESSENTIALLY CYLINDRICAL PINS, SAID PINS BEING ARRANGED SO THAT THE OUTER SURFACES THEREOF ARE CONTACTING AND THE AXES THEREOF ARE SUBSTANTIALLY IN PARALLEL, 